This study is for AIDS patients who have done well on combination drug therapy that includes one or two protease inhibitors. The study is designed to learn whether people can also do well with a switch in drugs to a different combination that does not include a protease inhibitor. This regimen is called maintenance therapy, because the treatment is designed to keep the subject's viral load as low as it is now. Earlier studies of maintenance therapy did not work, possibly because one or two of the drugs that were part of the original therapy was used and the original therapy lasted only 3 to 6 months.This study will use three drugs different from your original drugs. The primary objective of this Phase II, randomized, open-label study is to gather data about rates of HIV-1 viral suppression in subjects randomized to one of three arms: ddI(didanosine)/d4T(stavudine)/hydroxyurea, ddI/d4T/efavirenz or continued therapy with a protease inhibitor-containing (PI) regimen. The study aims to determine whether maintenance therapy can keep the viral load as low for as long a time as the PIs; the safety, tolerabiliy and toxicities of the regimens; and if maintenance therapy becomes ineffective and viral load increases, whether the PI therapy will work again.